1. Field of the Invention
The present invention relates to a blood pressure measurement device, and more particularly to a blood pressure measurement device that measures blood pressure taking into account congestion occurred at a peripheral side of the measurement location.
2. Description of the Related Art
Blood pressure is one indicator for analyzing circulatory diseases and is effective at preventing diseases of the cardiovascular system such as strokes, heart failure, heart attacks, and the like by performing risk analysis based on blood pressure.
Recent research indicates that blood pressure measured at home (home blood pressure) is more useful in the diagnosis of circulatory diseases than blood pressure measured by a health care facility (casual blood pressure). In conjunction with this, electronic sphygmomanometers that can be used at home are growing in popularity.
Oscillometric methods and microphone methods are mainly used as measurement principles for electronic sphygmomanometers for home use. With oscillometric methods, a cuff is wrapped around a measurement location such as an upper arm and the pressure inside the cuff (cuff pressure) is quickly increased to a predetermined pressure (for example, systolic blood pressure+30 mmHg) and then the cuff pressure is gradually decreased. Volume change occurring in the artery at that time is detected as a slight pressure fluctuation (pressure pulse wave amplitude) superimposed on the cuff pressure. The cuff pressure detected when the pressure pulse wave amplitude suddenly increases determines the systolic blood pressure, and the cuff pressure detected when the pressure pulse wave amplitude suddenly decreases determines the diastolic blood pressure. Furthermore, blood pressure may also be determined from the detected pressure pulse wave amplitude at the time when the cuff pressure gradually increases. An electronic sphygmomanometer that uses an oscillometric method is represented in, for example, Japanese Unexamined Patent Application No. S62-268532
Meanwhile, with microphone methods, similar to that with the oscillometric method, a cuff is wrapped around a measurement location such as an upper arm, and the cuff pressure is quickly increased to a predetermined pressure (for example, systolic blood pressure+30 mmHg) and then the cuff pressure is gradually decreased. Sounds generated in conjunction with blood flow of an artery as cuff pressure is adjusted by increasing or decreasing pressure, so called Korotkoff sounds, are detected by a microphone embedded within the cuff. Based on the detected result, the cuff pressure detected at the time that the Korotkoff sounds appear determines the systolic blood pressure, and the cuff pressure detected at the time when the Korotkoff sounds weaken or disappear determines the diastolic blood pressure.